AMSAT-LU Satellite Data

AO-27 AMRAD

Catalog number: 22825
Launch Date: September 26, 1993
Status: Semi-Operational

John, K6YK, reports to ANS:
Current AO-27 Status: Manual (Batteries are Low)
May 17th, 2004 UTC We are back in eclipse season and the batteries are low. We will have it back on once they charge back up.

The latest information on AO-27 from control operator Michael Wyrick, N3UC (former N4USI), can be found at http://www.ao27.org

An AO-27 question-and-answer page is available on the AMSAT-NA web site, with updates by Ray, W2RS. The URL is http://www.amsat.org/amsat/intro/ao27faq.html

AO-27 is an "FM Repeater" in space. It essentially consists of a crystal controlled FM receiver operation at 145.850 MHz and a crystal controlled FM transmitter operating at approximately 436.795 MHz. Output power of the transmitter can be set to over 1 watt (rarely used), 0.5 watts (normal operation), or under 0.1 watts (exciter only). The uplink antenna is the linear polarized whip on the top face of the spacecraft and is shared with the commercial payload's receivers. The downlink antenna is a 1/4 wave whip mounted on the bottom face of the spacecraft. Polarization is nominally linear, the rotation and revolution of the spacecraft and propagation effects will cause the actual signal polarization at a ground station to vary widely during a pass.

Because of the satellite's limited power budget and a desire to maintain sufficient battery capacity for as many years as possible, the amateur transmitter on AO-27 is on for only part of the daylight portion of each orbit. As of September 1998, the satellite passed its five year design goal with minimal signs of battery degradation, so this operating philosophy appears to have been successful.

AO-27 is available on daylight passes over the Northern Hemisphere. The "TEPR" States describe the amount of time (in minutes) when the spacecraft enters and leaves sunlight. TEPR numbers are adjusted every few months to account for the seasonal North/South movement of the latitudes where AO-27 enters and exits sunlight. Chuck Wyrick, N1UC (formerly KM4NZ), provides an Explanation of TEPR States. Most tracking programs will provide a reading or display the necessary info to predict if AO-27 will be "on" during a pass.

For further information about AMRAD contact:

AMRAD
P.O. Drawer 6148
McLean, Virginia, USA, 22106-6148
http://www.amrad.org

[ANS thanks John, K6YK, for this week's AO-27 report]
[06062004]436.795,145.850,0,FM-N,FM-N